1. Field of the Invention
The present invention relates to a composition for protecting cells against radiation, comprising hesperidin or pharmaceutically acceptable salts thereof as an active ingredient.
2. Description of the Related Art
Humans are incessantly exposed to ionizing radiation, such as cosmic rays and radiation emitted from naturally occurring radioactive species or various artificial sources. Ionizing radiation now finds a broad range of applications in various industries including electric power production, development of new, various high-yield crops, sterilization, and elongation of food shelf life (food radiation). In fact, the wide application of ionizing radiation makes exposure thereto unavoidable for humans.
Also, ionizing radiation is a powerful weapon in the treatment of various cancers because of the ability thereof to eliminate tumors or inhibit the growth of cancer cells. are treated by radiotherapy. Despite the excellent therapeutic index thereof, however, radiotherapy may give rise to damaging the normal tissue of persons surviving cancer [Meister, M., 2005. In: The health effects of low-level radiation. American Council on Science and Health, New York, pp. 2-4]. Radiotherapy has made significant contributions to the treatment of cancer and thus the life extension of cancer patients, but many of the patients who have undergone radiotherapy are found to develop secondary cancers some of which are far severer than the primary cancer was [Littler M. P., 2001. Cancer after exposing to radiation in the course of treatment for the benign and malignant disease. Lancet Oncol. 2, 212-220].
Therefore, there is an imperative need for a method by which cells can be protected from injury due to exposure to radiation.
Some studies reported that cell damage by ionizing radiation is dominantly mediated by free radicals and produced reactive oxygen species [Weiss, J. F., Landauer, M. R., 2003. Protection against ionizing radiation by antioxidant nutrients and phytochemicals, Toxicology. 189, 1-20]. Ionizing radiation ionizes water, an important cell constituent, into primary water radical species. The primary radical species created during the decomposition under radiation of water reacts with molecules to form secondary radical species such as H2O2 and O2−, which are transferred to cellular targets, such as DNA, proteins and membranes, leading to the activation of several proto-oncogenes or to cell death [Mates, J. M., Sanchez-Jimenez, F. M., 2000. Role of reactive oxygen species in apoptosis: implications for cancer therapy. Int J Biochem Cell Biol. 32, 157-170]. Because free radicals play an important role in the initiating and progressing of radiation-induced toxicity, the use of antioxidants in foods or as therapeutics may prevent radiation-induced injuries to cells. Recently, studies have been conducted into the potential use of flavonoids as free radical scavengers for the prevention of oxidative damage [Van Acker, F. A., Schouten, O., Haenen, R. M., van der Vijh, W. J. F., Bast, A., 2000. Flavonoid can replace tocopherol as an antioxidant. FEBS Lett. 473, 145-148].
Hesperidin (hesperetin-7-rhamnoglucoside) is a flavonoid having a molecular formula of C28H34O15 with a molecular weight of 610. It has a pale yellow or yellowish appearance as a crystal or crystalline powder and gives neither scent nor taste. The flavonoid hesperidin is a flavanone glycoside (glucoside) comprised of the flavanone (a class of flavonoids) hesperitin and the disaccharide rutinose. Citrus fruits such as lemons and oranges, particularly unripe fruits, are abundant in hesperidin. The peel and membranous parts of these fruits have the highest hesperidin concentrations which amount to 1.5˜3%. This flavonoid is found in green vegetables, as well. Hesperidin is thought to reduce capillary permeability and was known as vitamin P. In vivo, hesperidin has antioxidant, anti-inflammatory, hypolipidemic, vasoprotective and anti-carcinogenic and cholesterol lowering actions. Hesperidin improves the health of capillaries by increasing capillary resistance and reducing capillary permeability. Hesperidin is used to reduce hay fever and other allergic conditions by inhibiting the release of histamine from mast cells. The possible anti-cancer activity of hesperidin could be explained by the inhibition of polyamine synthesis. Some studies have showed that hesperidin added to the diet not only lowered serum and hepatic cholesterol, but also inhibited bone loss by decreasing osteoclast number in ovariectomized mice. According to the reports of other studies, hesperidin was observed to have great positive effects on the removal of the contaminant cadmium through feces, significantly lower blood glyceride and cholesterol levels and significantly increase blood HDL-cholesterol.
With regard to hesperidin, a composition for inhibiting platelet aggregation containing hesperidin or hesperetin is disclosed in Korean Patent No. 276979, a cosmetic containing alpha-glycosyl hesperidin in Korean Patent No. 184244, and a composition for lowering blood pressure in Korean Patent Application Laid-Open Publication No. 1999-0039368. Nowhere so far has the cytoprotective activity of hesperidin against radiation been mentioned in the prior art.
Leading to the present invention, intensive and thorough research into the protection of cells from radiation-induced injuries, conducted by the present inventors, resulted in the finding that hesperidin is cytoprotective against radiation.